Nissan: Frontier Heater problems

I have a 2001 frontier crewcab and I have noticed an odd heater problem.
The engine will get hot and start to blow heat from the heater vents as it
should in the winter. When I come to a stop, within 10 seconds, the warm
heater air gets cold and stays cold until I start moving again. The heater
fan is running, the engine temp is fine and the heater core is not leaking.
I am looking for any input anyone might have.

Thanks,

Joel

I thought of that the other day and topped it off. It was low and that
worries me. I appreciate the help and input. I knew I could count on this
group. BTW, love the email name. Will have to give it a good look over
when I change the oil soon. Thanks again.

Joel
"NissTech" <com> wrote in message
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it 
warm